Ursa Major time lapse photography

I know that my D7100 isn’t the best available tool for nighttime time lapse photography, but it is what I got. I shot few time lapses last night before it got dark and I thought why don’t I try what you can do with it.

I set my camera to shoot 400 frames, but as I had shooted few others time lapses before, it run out of battery after 155 frames. So this is what I got: